1. Field of the Invention
This invention is concerned with swimming pools, and in particular with means of cleaning and removing debris from swimming pools.
2. Description of the Related Art
Swimming pool suction cleaning devices of the prior art typically comprise a rectangular housing having a substantially planar bottom with a centrally located suction hole connected to a suction means via a hose attached to a tubular outlet on the housing top. The cleaning device is moved along the pool bottom so that the housing bottom remains substantially parallel and in close proximity with the bottom of the swimming pool while water from the swimming pool is sucked through a small bottom gap between the housing bottom and the swimming pool bottom. In some cases, wheels or housing bottom protrusions are used to provide a bottom gap that is more uniform and/or optimum in width. The housing may also be made of a flexible material so that the housing bottom tends to conform to curved areas of the pool bottom. Such devices are reasonably effective for removing dirt from the pool bottom but cannot capture debris larger than the bottom gap of the device. And the bottom gap is typically very small so as to provide the fast water flow rate needed to efficiently remove dirt from the swimming pool bottom.
Various modifications designed to improve the effectiveness of pool cleaning devices have been described in the prior art. For example, U.S. Pat. No. 5,048,149 to Heinen (issued 17 Sep. 1991) describes a pool cleaning device having a fixed brush attached along the leading edge of the housing so as dislodge dirt particles by sweeping the pool surface. Such brushes tend to push debris along the pool bottom rather than direct it to the suction hole.
Some pool cleaning suction devices of the prior art provide the needed narrow bottom gap via a lip around the perimeter of a housing bottom that circumscribes a bottom suction cavity containing a means for improving the effectiveness of the device. For example, U.S. Pat. No. 5,842,243 to Horvath et al. (issued 1 Dec. 1998) describes a pool cleaning suction device having a fixed brush pivotally mounted inside a bottom suction cavity such that the brush angle changes depending on the direction of movement of the device. U.S. Pat. No. 4,402,101 to van Zyl (issued 6 Sep. 1983) describes a pool cleaner device comprising an elongated brush rotated by an electric motor and located inside the bottom suction cavity so that dirt dislodged by the sweeping action of the rotating brush is effectively captured by the device. U.S. Pat. No. 6,942,790 to Dolton (issued 13 Sep. 2005) describes a pool cleaning suction device having two cylindrical scrubbing brushes mounted inside the bottom suction cavity that are rotated in opposing directions by a mechanical drive motor.
Such prior art devices are ineffective for removing bits of debris that are too large to pass through the narrow bottom gap between the housing bottom perimeter and the pool surface. Tree leaves are particularly difficult to capture using the devices of the prior art since the leaves are often highly non-planar so that they do not readily pass through the small bottom gap needed to vacuum dirt from pool surfaces. U.S. Pat. No. 5,664,275 to Sebor (issued 5 Sep. 1997) describes a pool cleaning suction device having an oscillator that periodically widens the bottom gap around the perimeter of a bottom suction cavity so as to periodically capture larger bits of debris. The Sebor '275 device is relatively complicated and does not provide continuous capture of debris.
U.S. Pat. No. 5,001,800 to Parenti et al. (issued 26 Mar. 1991) describes a pool cleaning suction device comprising a hydraulic turbine motor that drives two pairs of wheels having rubber band treads to provide locomotion, and drives a cam that raises one of the pairs of treaded wheels off the pool bottom to provide steering. Parenti '800 further describes use of the motor to drive rotation of a cylindrical brush located along the front of the housing but does not indicate that it provides improved effectiveness for capturing large bits of debris. The Parenti '800 device is relatively complicated and is not well suited for use in small residential swimming pools.
U.S. Patent Application Publication 2006/0174430 to Pareti (published 10 Aug. 2006) describes a swimming pool cleaning device that includes an ultrasonic wave generator in a housing bottom cavity designed to dislodge adherent materials from the submerged pool surfaces. The Pareti '430 device further comprises an electric motor that drives rubber treads via drive wheels to move the device along the pool surface, and three rotary brushes. The larger brush is located within the housing bottom cavity and the two smaller brushes are located outside the housing on the leading and trailing edges. The Pareti '430 device is designed to remove recalcitrant deposits, such as limestone scale, rust, sludge and weeds, via a combination of ultrasound and scrubbing. This device is relatively complicated and is not well suited for use in small residential swimming pools. The Pareti '430 publication provides no indication that the device provides improved effectiveness for capturing large bits of debris.
As evident from the examples above, prior art efforts to improve pool cleaning devices have focused on removal of dirt and scale deposits rather than debris. Consequently, rotary brushes incorporated in prior art devices have typically been located within the suction cavity where they are ineffective as aids for capturing debris too large to directly pass through the bottom gap of the device. Prior art pool cleaning devices also tend to be powered by an electric or hydraulic motor and often include steering mechanisms, making them too bulky, complicated and expensive for use in small residential swimming pools. There is a need for a relatively simple pool cleaning device that effectively removes both dirt and debris, especially tree leaves, from swimming pool bottoms.